A simple numerical treatment of aperture integrals involved in the open-ended coaxial line method for validating the dielectric properties of tissue-equivalent liquid

The open-ended coaxial line method is attractive to the dielectric property measurement of tissue-equivalent liquid used in the Specific Absorption Rate (SAR) test. To evaluate the probe aperture admittance which is in a variational form, a full numerical treatment to the involved aperture integrals is presented. In this technique, the singular static integral on the source domain is converted into a well-posed line integral over the circumference boundary, which gives the formulation well suited for numerical implementation. The calculations are verified with the reported results for several coaxial probes.